Besides its apparently greater size, _Berardius bairdii_ differs from _B. arnuxii_ in various cranial and other osteological characters, as well as in external proportions, and is to be regarded as a distinct species. The external measurements of the St. George Island specimens reduced to percentages of the total length and compared with similar measurements of a specimen of _B. arnuxii_ described by Hector, are as follows: _External dimensions of Berardius bairdii and B. arnuxii._ Column Headings: _bairdii._ A: 49726 St. George Island, Alaska, (Judge), female adult. B: 49727 St. George Island, Alaska, (Judge), male imm. _arnuxii._ C: Wellington, New Zealand, (Hector), male. Measurements. A B C ft. in. ft. in. ft. in. Total length 40 2 25 5 27 6 per per per cent. cent. cent. Distance from tip of snout to blowhole 10.8 11.8 12.8 Distance from tip of mandible to corner of 6.0 6.9 [a]6.1 mouth Breadth of flukes from tip to tip 25.3 24.6 19.1 Length of pectoral fin along outer edge 12.4 13.4 9.4 Distance from anus to “end of body” 29.0 29.8 [34.0] Height of dorsal fin 2.5 2.4 3.0 Distance from anterior base of dorsal fin to 29.7 29.2 [34.6] “end of body” [a] “Length of gape.” The measurements of these specimens of _bairdii_ agree well together. The specimen of _arnuxii_ appears to have had narrower flukes, shorter pectoral fin, and a rather higher dorsal fin, situated farther forward than in _bairdii_. Measurements of a larger number of specimens might show that some or all of these differences of proportion are elusive, but it will be observed that in the Wellington specimen of _arnuxii_, recorded by Doctor Haast, the breadth of the flukes is only 21 per cent of the total length. The pectoral fin is said to be only 19 inches long, or only 5.2 per cent of the total length, but the manner of taking the measurement is not mentioned.